The polymerization of olefins, particularly lower .alpha.-olefins, to produce polyolefin polymers has become an industry of substantial significance. The polyolefin polymers have gained widespread commercial acceptance because of the relatively low cost of the polymers and the desirable properties they possess. Moreover, a wide variety of such properties are available depending in part on the choice of monomer to be employed in the polyolefin production. There are some instances, however, where it is desirable to modify the properties of a polyolefin polymer in order to meet the requirements of some particular application. One such method of modification is by the production of copolymers of more than one olefinic monomer. For example, a random copolymer of ethylene and propylene demonstrates properties of elasticity that are not available from either ethylene or propylene homopolymer.
An alternate method of modifying the properties of a polyolefin polymer is through the provision of a polymer blend, e.g., blends of a polyolefin with another polyolefin or with other polymeric materials. For example, U.S. Pat. No. 4,189,519 describes a blend of a copolymer of ethylene and an unsaturated ester with a high molecular weight polybutene. The blend demonstrates better heat sealing properties than either single blend component.
Polymeric materials of suitable properties have shown substantial utility in the field of packaging as the use of plastic containers becomes more widespread. A substantial proportion of plastic containers and film wraps have been made from polyvinyl chloride. However, with the possible health and environmental problems associated with the use of polyvinyl chloride becoming more apparent, the use of other polymers or polymeric compositions of properties similar to those of polyvinyl chloride has become of wider interest. Polymers and copolymers of poly(1-butene), as well as blends thereof, have shown substantial utility in packaging applications, particularly those involving film. By way of illustration, U.S. Pat. No. 3,817,821 describes blends of polyvinyl alcohol and poly(1-butene) for packaging films. U.S. Pat. No. 3,879,492 discloses blends of poly(1-butene), styrene-butadiene copolymers, high and low density polyethylene and polyisobutylene. These and other blends of poly(1-butene) with other polymeric materials are known to have properties useful in packaging applications and better than those of poly(1-butene) when used alone. However, it would be of advantage to provide additional blends of poly(1-butene) and other polymers, where the blends demonstrate properties which are improved and also similar to those of polyvinyl chloride.